Fig 1.
Study site and scientific platform.
Location of the Kaw Marshes within French Guiana and picture of the scientific platform (6 x 4 meters) with its two metal boats. Reprinted with permission from S Caut.
Fig 2.
Satellite transmitter attached to a black caiman’s head.
Photograph of a male black caiman (Melanosuchus niger; M2; TL = 3.2 m) with an Argos satellite transmitter glued to the front of its head. Reprinted with permission from S Caut.
Table 1.
Summary statistics describing the movement patterns of the one female (F1) and three male (M1-M3) black caimans fitted with satellite transmitters.
Length (meter) = the total length of the caiman; Tracking days = the total days of GPS tracking; GPS points = the total number of GPS localisation points obtained with four satellites over the tracking days; Distance (meter) = Total distance travelled by the caiman over the tracking days; KUD (meter2) = the 95% and 50% volume contours of the kernel utilisation distribution.
Table 2.
Number of black caimans sampled by age class (A, B, C, D) for the three sampling periods (D1, W2, W3).
*This individual was caught but not sampled because it was too small (TL = 39 cm).
Fig 3.
Mean (+SE) δ15N and δ13C values for black caimans in different age classes.
Values are represented for the three sampling periods (D1, W2, W3) and the three tissues sampled (gray = muscle, white = RBCs, and black = plasma). The age classes are represented in the same order for each sampling period (A, B, C, D, with the number of caimans sampled). *During W3, only muscle was sampled for the sole individual captured in age class A.
Table 3.
Stable isotope values (δ13C and δ15N, mean ± SE %∘) for the different ecosystem compartments sampled across seasons (D1, W2, W3).
Factorial analysis of variance exploring the effect of season (D1, W2, W3) on the stable carbon and nitrogen isotope values of each compartment. Amphibians were present, but none were caught during the dry season. For the birds, the inundated forest provides habitat for nest building that is used by diverse water bird species and most notably the Agami heron (1,500 breeding pairs). Caimans prey upon fallen chicks and juvenile adults. These potential prey were only present during the wet season.
Table 4.
Variation in black caiman isotopic values.
Factorial analysis of variance exploring 1) the effect of season (D1, W2, W3) and tissue type (muscle, plasma, and RBCs) on stable carbon and nitrogen isotope values for black caimans in intermediate age classes (B, C) and 2) the effect of tissue type (muscle, plasma, and RBCs) and total length (TL) on stable carbon and nitrogen isotope values for black caimans in all age classes (A,B,C,D). In italics are the results that were significant in the full model.
Fig 4.
Relationship between black caiman δ15N values and total length (TL).
Each circle represents one individual (white = RBCs, gray = muscle, and black = plasma). The equation, the coefficient of determination, and the best-fit curve are shown for the significant models (muscle F1,72 = 103.80, P < 0.001; plasma F1,72 = 69.51, P < 0.001; and RBCs F1,72 = 90.43, P < 0.001).
Fig 5.
Mean (± SE) δ15N and δ13C values for the black caimans and the different ecosystem compartments of Agami Pond.
The symbols represent each ecosystem compartment. The black circles are the black caimans belonging to different age classes (A, B, C, D); the white squares are the different ecosystem compartments during the wet and dry seasons; and the gray square is the bird compartment (only present during the wet season).
Fig 6.
Movement patterns of the four black caimans fitted with Argos satellite transmitters.
(A) Map and recorded locations of the black caimans (F1, M1, M2, M3); (B: the scale half of A) KUD 50% (solid color) and KUD 95% (hatched color) calculated from the location data.